1. Field of the Invention
The invention relates to a bioreactor for culturing microorganisms which has a reactor vessel, a plurality of gas-introduction tubes and a gas-introduction system for introducing gas into a culture medium in the gas-introduction tubes via injectors.
2. Description of the Related Art
It is known to use photobioreactors for culturing phototropic microorganisms, in particular for producing microalgae. For example, WO 00/61719 discloses that a high biomass productivity is a problem of optimum light distribution per unit volume. The known bioreactor has a reactor compartment made of translucent material, the enclosing end of which of the reactor chamber cross section is designed, for example, in a meander shape or sinusoidally to increase the surface area. Also, this publication discloses constructing the reactor chamber as glass tube into the interior of which project glass extensions.
It is a disadvantage that such a design of the enclosing ends of the reactor chamber is very complex and cost intensive.
Furthermore, DE 197 47 994 C1 discloses a bioreactor having U-shaped reactor elements. The U-shaped reactor elements consist of vertical transparent tubes which, at their lower ends, are connected to one another via a U-shaped leg. A tube of a reactor element acts as gas-introduction tube. For this, gas-introduction nozzles are provided as injectors for introducing carrier gases which simultaneously act for the transport of the culture medium in what is termed the airlift system. In the vertical direction, at the top end of the reactor elements, a reactor vessel is attached which forms a biomass collection chamber. The culture medium is heated or cooled via the reactor vessel which also simultaneously acts as expansion vessel and which has an exhaust gas apparatus.
It is a disadvantage of the known bioreactor that, owing to the arrangement of the U-shaped reactor elements, complete emptying of the bioreactor is relatively complex, since each of the reactor elements must be emptied separately. Also, it has been found that a spatial separation of heating or cooling device and exhaust gas apparatus, which would be advantageous for the closed-loop and open-loop control of the culture process, is only possible with difficulty in the known embodiment.
It is therefore an object of the present invention to improve the known apparatus in such a manner that its handling is simplified and that the closed-loop and open-loop control of the culture process can be improved.